Thiruvananthapuram City Corporation Mayor Arya Rajendran said the operation was temporarily stopped on Sunday and will commence Monday morning with the naval team undertaking an assessment using sonar equipment to accurately locate the waste and debris inside the tunnel of the canal located on the Railway premises.

Joy (47), a temporary cleaning worker employed by a railway contractor, went missing while clearing the waste-filled canal criss-crossing through the heart of the capital city on Saturday.

He and two other workers were engaged in cleaning the Thampanoor part of the canal near the railway station when the water flow increased due to heavy rainfall, sweeping him into a 200-metre-long tunnel below the tracks of the platform at the central railway station.

The daring rescue attempts by the NDRF, the fire force, police and the city corporation workers in the canal tunnel filled with massive loads of hard waste so far failed to yield any results.

The Navy team, which reached the state capital on Sunday night, held a meeting with district authorities and the Railways and decided to examine the tunnel on Monday assisted by the scuba team of the fire force.

After a meeting between various authorities, the mayor told the media that special observation teams would monitor the entry and exit points of the canal throughout the night.

"The team will monitor the water level and the flow of the water and the waste," she said.

District Collector Geromic George said further actions will be taken after the assessment of the Navy on Monday morning.

A ministerial delegation, comprising Local Self Government Department minister M B Rajesh, Industries Minister P Rajeeve and Power Minister K Krishnankutty visited the site late Sunday night to assess the situation.

Meanwhile, the municipal and Railway authorities indulged in a blame game over the incident.

Railway Assistant Divisional Manager Viji told the media that there were no lapses on behalf of the Railways.

The official said they have limitations in cleaning the part of the canal under its premises and blamed the city corporation for the waste accumulated inside it.

On its part, the city corporation released multiple documents including notices recently issued by it and the district collector directing the Railway authorities to clear the tunnel of the canal inside its premises as part of pre-monsoon cleaning.

Speaking to the media, Rajesh said the incident happened inside the railway premises.

"It is clear that no one (city corporation or the district authority) can interfere in the matters inside the Railway premises. Various letters and notices issued by the corporation asking to clean the tunnel have come out now. the latest notice was issued in June as a last warning before initiating legal action," Rajesh said.

Railway Assistant Divisional Manager Viji claimed that the waste was not from its premises but from Thiruvananthapuram city that was coming through the canal.

"We (Railways) have even installed a mesh to prevent the waste from entering the tunnel inside the railway premises. We have limitations in cleaning the tunnel under the railway lines. We are not experts.

"They (city corporation) should do this (cleaning). The corporation could have coordinated well," the officer told the media.

Meanwhile, the city mayor denied the charges and said the Railway was releasing the wastewater generated into the canal instead of treating it in a sewage treatment plant.

"Railway claims that it has facilities to dispose of the waste generated there. Are they ready to prove it? Yesterday when we used the robot to clean the manhole between the platforms, we all saw the plastic waste from various Railway brands," Arya said.

She said the city corporation would inspect whether there was any deliberate attempt to release the solid and faecal waste directly into the canal.

"Can the railway show any treatment plants inside its premises to treat the faecal waste or other waste water generated inside its premises in Thiruvananthapuram," the Mayor asked.

The opposition Congress trained its gun on the ruling CPI(M).

Leader of Opposition V D Satheesan said the government failed at pre-monsoon cleaning.

"If there is a dispute between the Railways and the city corporation, the government should have interfered to resolve it. The apathy of the government is evident from this," Satheesan said.

The statement by Satheesan was criticised by Minister V Sivankutty, who said the remarks were immature and inhumane.

A worker employed by a Railway contractor went missing in an incident that happened on its premises, but the state government was doing everything it could to rescue him, Sivankutty said.

"The Railway has never given permission for the corporation or the state government to interfere in the matters (cleaning of the tunnel inside the premises) there. The contract workers were deployed by the Railway without taking any safety precautions," Sivankutty said.

The minister said disregarding all the efforts of the state government to rescue the worker, the Leader of Opposition was determined to accuse the corporation even without visiting the site.

Rajesh said the priority was for the search and rescue of the worker.

"The incident happened inside the railway premises where they have the authority. Rest of the matters can be discussed later," Rajesh added.

The canal and the tunnel entry are filled with plastic and hard waste and the rains were hampering the rescue operation, officials had said.

The NDRF and the fire force members were seen working tirelessly for the past 36 hours in waist-deep wastewater clearing the debris to facilitate the scuba divers to dive in search of the missing worker.